Recently, development of automated manual transmissions, which may achieve both driving convenience of automatic transmissions and high fuel efficiency and power efficiency of manual transmissions, has been actively carried out. A dual clutch transmission (DCT) is one kind of automated manual transmission.
An automated manual transmission is a system which automatically executes clutch operation and gear shifting based on a manual transmission, and such operations may be carried out by actuators which are operated hydraulically or by motors. Particularly, dry clutches are used and configured such that, when the dry clutch is controlled using a motor, the clutch is controlled through a link structure. If a link fails or the clutch become stuck, an engine may stall, creating a potentially adverse situation. Therefore, a clutch failure needs to be accurately diagnosed.
FIG. 1 is a graph illustrating a situation in which a clutch 1 is stuck and cranking of an engine is carried out in a state in which the engine and the clutch 1 are almost directly connected. FIG. 1 illustrates that, as an engine speed increases due to cranking of the engine, the speed of the clutch 1 is increased in synchronization with the speed of the engine. Therefore, whether or not the clutch 1 is stuck, i.e., fails, may be judged based on the synchronized state between the speed of the clutch 1 and the speed of the engine.
However, if a hybrid vehicle is used and the vehicle is driven in an EV mode, an engine is turned off, and thus it may not be possible to diagnose whether or not a clutch is stuck based on synchronization of the speed of the engine and the speed of a transmission clutch. Thereby, a misdiagnosis indicating that gear engagement is in a normal state may be made, thus resulting in stalling of the engine or another adverse situation.
The above description has been provided to aid in understanding of the background of the present disclosure and should not be interpreted as conventional technology known to those skilled in the art.